In a typical cellular radio environment the signals between a base station and subscriber terminal equipment propagate on several routes between a transmitter and a receiver. This multi-path propagation is mainly caused by signal reflections from surrounding surfaces. Signals traveling on different routes arrive at the receiver at different times because of a different propagation delay. This holds true for both directions of transmission.
In the receiver the multipath propagated signal may be equalized, i.e. the received signal is processed in such a manner that the effect of multipath propagation can be reduced.
In modern communication systems the processing of a received signal is a challenging task due to high data rates and complex modulation methods used in the transmission. For example, equalization in systems employing High Speed Downlink Packet Access (HSDPA) requires processing and calculating of large matrices. Inversion of a large matrix in particular is a complex task.
In many systems where matrix inversions are calculated in connection with equalization, Discrete Fourier Transform (DFT) is applied. The calculation of a complex DFT algorithm requires a large amount of processing. This requires large computational power from receivers. The computational needs grow larger as the need for faster data rates and larger bandwidths increase in the future evolutions of present telecommunication systems.